1. Field of the Invention
The present invention pertains to liner elements for closure caps utilized for hermetically sealing bottles, jars and like containers employing removable closure members to hermetically seal the dispensing end of the container. More particularly, the invention relates to an improved liner element which provides greater versatility in the selection of various polymeric liner materials which may be compatibly employed with and bonded to various types of closure caps, regardless of the types of material from which such caps are fabricated, such as aluminum, tin or chrome-plated steel, plastic or the like. In other more particular respects, the present invention also relates to an improved liner element which is adapted to carry distinctive or promotional markings, logos, color patterns, emblems, designs and messages so that upon removal of the closure cap from a container such markings may be visibly discernible within the cap without necessitating prior removal of the liner element from within the closure cap.
2. Description of the Prior Art
In the packaging of various comestibles and beverages in bottles, jars and like containers, it has become conventional practice to utilize closure caps having a pliant, protective sealing liner covering the interior end surface of the closure cap. Upon tightly securing the closure cap onto the dispensing end of its intended container, the liner is designed to press tightly against and yieldably conform to the surface configuration of the dispensing end of the container to thereby form a protective hermetic seal capable of maintaining the container's contents in a flavorful and wholesome condition until such time as consumption of the container's contents is desired. Such types of closure caps are, of course, well-known and commonly have outer shells fabricated from such materials as aluminum, tin or chrome-plated steel, and plastic. Typically, the entire interior surfaces of such closure caps, and particularly those fabricated from aluminum and tin or chrome-plated steel, are overcoated with an organic lacquer or varnish film coating which is heated to form a tough, baked-on film of organic sizing material. Among other well-known sizing materials commmonly employed for such purposes are solvent-containing vinyl phenolic coatings, and modified polyvinyl chloride coatings, such as, for example, vinyl chloride/vinyl acetate copolymers having an oleoresinous modifier, such as a tung oil modified phenol-formaldehyde, dissolved in a suitable heat dissipatable solvent; the latter coating material being described in U.S. Pat. No. 3,411,650. These specifically mentioned sizing materials have been found to be especially suitable since they not only adhere tenaciously to the interior surfaces of both aluminum and tin and chrome-plated steel closure caps, but also provide sidewall surface lubricity which reduces the manual torque required in removing threaded or similar twist-off types of closure caps from containers. No less significantly, these various vinyl phenolic and modified polyvinyl chloride sizing compositions have been found to be an exceptionally effectual and compatible bonding media for heat-bonding to commonly employed plastisol sealing liners.
In the past, commonly employed plastisol sealing liners have customarily included vinyl, and particularly vinyl or vinylidene chloride, as constituent components of the liner composition. Moreover, while these plastisol liner materials have achieved substantial commercial acceptance as an effective hermetic liner material, substantial interest has been expressed by the packaging industry, as well as the United States Federal Food and Drug Administration, in the development of alternative hermetically sealable liner materials which are compatible with packaged products intended for human consumption. Among other advantages, the development of alternative liner materials provides the promise of less restricted material supply sources and reduced material cost. Additionally, such alternative liner materials offer the capability of greater versatility of liner properties and characteristics so that the liner materials may be better tailored to the particular packaging needs or requirements desired. Consequently, intensified efforts have been directed towards the formulation and development of commercially feasible, alternative closure liner materials which, in addition to possessing the hermetic sealability characteristics of plastisol liner materials heretofore commonly utilized, also possess a highly acceptable degree of compatibility with comestible products and beverages with which they may be employed for packaging purposes.
For various reasons, however, many of the newly developed liner materials have been found to be unsuitable for use with conventional aluminum or plated steel closure caps since they do not effectively bond with the conventionally employed sizing materials employed on the interior surfaces of such closure caps, and thus cannot be securely bonded or retained within the closure caps. Without such secure retention within the closure, seal failure is likely to result as a consequence of displacement of the liner within or from the closure cap. For example, among others, copolymers of ethylene/vinyl acetate have been found to possess properties of inertness, durability and hermetic sealability which are known to render them especially suitable as liner materials for a diverse variety of comestibles and carbonated beverages. Unfortunately, however, as with various other newly developed liner materials, these ethylene/vinyl acetate copolymers possess properties which preclude the formation of an effective bond to conventional sizing materials commonly applied on the interior surfaces of aluminum and plated steel closure caps. Thus, a great need exists for the development of an effective means of achieving a bonding compatibility between aluminum and plated steel closures utilizing conventional sizing materials and various newly developed polymeric liner materials such as, for example, the previously mentioned liner materials fabricated from ethylene/vinyl acetate copolymers.
More recently, both aluminum and chrome and tin-plated steel closures of the threaded, or twist-off, variety have achieved substantial market acceptance as convenience closures for various types of beverage bottles, and similar containers, used for packaging both carbonated and non-carbonated beverages. In the manner previously described, these convenience closures are likewise conventionally interiorly coated with a baked-on sizing composition to which conventional plastisol types of liners are heat-bonded and provide a hermetic seal to protect the flavor, wholesomeness and carbonation, if any, of the packaged beverage. Particularly in the soft-drink industry, there has been a sizeable trend and persuasive commercial interest in providing a convenience closure in which the interior of the closure is provided with distinctive markings, logos, symbols, color patterns, emblems or other various designs or messages which are visually discernible within the closure cap after its removal from a container. Such markings are frequently applied for aesthetic or promotional purposes. Also, closures containing such interior markings are suitable for use as children's trading items or as tokens which are redeemable for valuable prizes and gifts. In brief, closures provided with such interior designs, markings, or the like, are commercially desirable factors capable of influencing an increased market demand for various products, and particularly non-alcoholic beverages and soft-drinks which are in great demand and consumed in substantial quantities by children and adults alike.
In the past, attempts to provide closure caps having interior markings, logos, designs, etc. have ordinarily been difficult and costly and have necessitated the application of such markings, etc. directly upon the metal portion of the closure or upon the closure sizing composition so that they appear on the interior end surface of the closure prior to application of the plastisol liner material, which in such instances is selected to possess substantial transparency after curing. Alternatively, attempts have been made to apply such markings, designs, etc. on the unexposed surface of the plastisol liner material which is to be bonded to the closure. In either event, the application of such markings to either the bare or sized metal surface of the closure or to the surface of the liner material entails an inordinately time-consuming and costly manufacturing operation. Due to the lack of surface absorbency of aluminum and plated steel, application of the selected printing ink, enamel, or other marking medium directly onto the unsized metal requires prolonged drying times and/or elaborate drying techniques and equipment. Moreover, to provide multiple color applications, each color must ordinarily be separately dried prior to the application of another color. On the other hand, in the event that the sizing composition is applied to the metal prior to application of the marking or printing medium; then, a delicate tailoring or match of drying and baking temperatures is required in order to properly dry the marking or printing medium and to properly bake the sizing composition on the metal. Moreover, if multiple color application is desired, even more time-consuming and complex temperature coordinated drying and baking procedures are necessitated. Alternatively, if the printing or coloring medium is applied directly to the surface of the liner material, as is customary, while the liner material is in sheet form, exacting registration and orientational problems are encountered to ensure proper subsequent location of the marking, logo, etc. within the closure cap. No less importantly, the residual unused portions of the sheet of liner material, from which the individual liner members are stamped out or otherwise removed, is ordinarily salvaged for reuse and thus is subject to objectionable contamination by the marking medium during subsequent reprocessing and reconsolidation of the salvaged material into reusable sheets of liner material.